<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<input type="text" value="" id="txt">
<script>
    //没有写完的代码
    function Person(){

    }
    Person.createObj = function(obj){
        var o =
    }
    Person.$ = function(id){
        return typeof id == 'string' ? document.getElementById(id):id;
    }
    Person.prototype.addVale = function(){
        this.obj.value = 'frank'
    }
</script>
</body>
</html>